3.4L Motor Swap Underway! - 986 Forum - The Community for Porsche Boxster & Cayman Owners

insite · 10-02-2010, 12:33 PM

okay, so necessity is the mother of invention. how to make a 996/boxster cam timing tool for ten bucks:

1. find a socket that just BARELY fits into this hole. for me it was a 21mm.

2. find a wood bore drill bit that BARELY fits into the socket. for me, it was 15/16.

3. cut the end off the drill bit & cut the tip off the drill bit, leaving about 5mm protruding from the tip.

4. put the cut piece into the socket. voila, you have a 1/2" drive porsche cam rotation tool.

now time your cams. more to follow.

chaudanova · 10-02-2010, 05:40 PM

^^ Brilliant! Love the innovation...

Cloudsurfer · 10-02-2010, 06:56 PM

Very ingenious indeed. Unfortunately, you are going to need more than just a tool to turn the cam to get it back into time. You really need the timing tools, and the auxiliary tensioners.

insite · 10-03-2010, 04:15 AM

Quote:

Originally Posted by Cloudsurfer

Very ingenious indeed. Unfortunately, you are going to need more than just a tool to turn the cam to get it back into time. You really need the timing tools, and the auxiliary tensioners.

what makes you think that? i understand the process fairly well, but i've never timed one of these.

Cloudsurfer · 10-03-2010, 10:45 AM

Quote:

Originally Posted by insite

what makes you think that? i understand the process fairly well, but i've never timed one of these.

Well, the first thing I would do is visually check if the chain did slip a tooth or not. If you put the engine at TDC, and the slot on the cam is parallel to the line of the head/ valve cover joint, you can be fairly certain it's in time (in your picture, it is not parallel, so if the crank pulley is at TDC you are likely off one tooth). If you pull off the oil extraction pump (take note of its orientation, as they use the same part for both banks, but in different orientation) in the head, you'll see a chainwheel, which is bolted to the exhaust cam by 4 10mm bolts. The chainwheel has slots to allow for adjustment. The intake cam (as I'm sure you know) is driven off the exhaust cam via a separate chain and this contains the VarioCam tensioner. So, if the timing is off on the exhaust, it is also off on the intake. The timing mark, which the timing tool fits into, is on the intake cam. The tool merely holds the cam stationary while bolted to the head.

Hypothetically, if the chain slipped one tooth, you could be able to remove the tensioner and move the chain over one tooth the other way and be done (you'd need the valve cover off for this) but I've never tried doing this. However, to actually time the engine, you must loosen those 4 10mm fasteners, and do the procedure. I would roll the engine over and check both sides if you get stuck doing this. The tool only fits into the cam one way, so if it won't fit on bank 1-3, it would fit into bank 4-6, so if you are timing bank 1-3, you'd have to roll the engine over a turn. When timing the whole engine, you time one bank, then roll the engine 360, then time the other. I then roll the engine several times and double check things. For a 5 chain motor, you do need the auxiliary tensioners, which place a precise amount of tension on the chains. Supposedly you can time a newer, 3 chain motor without these, but you do need the tensioners on a 5 chain motor.

The 10mm bolts holding the chainwheel to the exhaust cam should be in the middle of their adjustment range, so you should have plenty of range to move either way during the timing process. The easiest way of re-timing your one bank would be to move the crank until you can fit the timing tool into that side's cam, lock the tool down, loosen the adjustment bolts on the cam, then roll the engine backward and then forward (to take any potential slack out of the chain) until you hit TDC (you only want to move forward when coming up to TDC), lock the crank with the fixing pin, and then tighten the 4 10mm fasteners (10 pound torque if I remember). Then, roll the engine 2 full revolutions, and re-check.

Like I said, if you get stuck doing this, I would check both banks while you have the engine out of the car and it's pretty easy to do.

Personally, I find the way you time these to be very imprecise, as there is potential variation in way too many places (where the TDC mark is on the pulley, variation in machining those slots into the non driven side of the cam during manufacturing, variation in tolerances in the tool, etc) but short of figuring out "true" TDC with a dial gauge on piston 1 or 4, and knowing the overlap numbers, it is what it is.

Gilles · 10-05-2010, 11:18 AM

Quote:

Originally Posted by insite

what makes you think that? i understand the process fairly well, but i've never timed one of these.

Ok, after reading several times Cloudsurfer's excellent and detailed description, the $85/hr and the cardbox on the back of the SUV makes sense to me

insite · 10-05-2010, 12:32 PM

i talked to jake; he thinks the auxiliary tensioners are total bs and completely unnecessary.

i will be timing the motor with no special tools & will post the procedure w/ pics when i do so. if i don't get to it wednesday, it will be awhile; probably won't get to work on it again until the 16th.

clickman · 10-05-2010, 02:41 PM

Quote:

Originally Posted by insite

probably won't get to work on it again until the 16th.

Jeez, I don't know if I can wait that long. Talk about living vicariously through someone else!

Gilles · 10-15-2010, 11:33 AM

Quote:

Originally Posted by insite

probably won't get to work on it again until the 16th.

A friendly reminder, today is the 15th....!
so, get back to work

and Please share your notes..ha!

.

Gilles · 10-03-2010, 08:17 AM

Quote:

Originally Posted by Cloudsurfer

Very ingenious indeed. Unfortunately, you are going to need more than just a tool to turn the cam to get it back into time. You really need the timing tools, and the auxiliary tensioners.

Ok it seems that the cam on the picture has jumped one teeth, and the cam obviously is still connected to the timing chain.

Question, if you 'loose' the chain tension as much as possible, would this allow you to rotate the cam (jumping teeth on purpose, one at the time) until you get back to the timing mark?

The cam phasing I have done in the past has always been on 'belted' engines, never with a chain which must be much harder, is this doable at all?

Or do you have to remove the valve cover to remove the chain from the cam sprocket, re-align the cam and then re-install the chain?

My questions here are pure curiosity and personal learning purposes, no criticism intended to anyone else comments.
.